A conventional vehicle transmission includes an input member, an output member, and a gear box containing various clutches and gear sets. The input member receives input torque from an internal combustion engine and transfers it to the output member at a desired speed ratio via the clutches and gear sets. The output member ultimately powers a drive axle to propel the vehicle.
A clutch-to-clutch shift occurs in such a transmission via the release of a first clutch associated with the current speed ratio, i.e., the offgoing clutch, and coordinated engagement of a second clutch associated with a desired new speed ratio, i.e., the oncoming clutch. Closed-loop control of the release and engagement of the respective offgoing and oncoming clutches through the torque and inertia phases of a clutch-to-clutch shift helps avoid a perceptible interruption of power flow through the transmission.